Separator for storage batteries and method of making



OFFICE,

DAVID FOSTER GOULD, OF NEWARK, NEW JERSEY, ASSIGNOR TO GENERAL LEAD BATTERIES COMPANY, A CORPORATION 05 DELAWARE.

SEPARAT JR FOR STORAGE BATTERIES AND METHOD OF MAKING.

No Drawing.

To all whom it may concern;

Be it known the D I, DAVID F os'rrm GOULD, a citizen of United States, residing at Newark, county of Fssex, and State of New -Jersey, have inve ited new and useful Imrapid and capable of producing separators of the proper requiremerts z. e. porosity (so as to increase the fluid passages through the wood, thereby allowin diffusion of the acid through the cell an affording enlarged paths for the electric currentso that the resistance is reduced), long lite under Working conditions in a battery and a low content of the various gums, resins, coloring matters and substances of similar nature which occur in wood and whichmay be called impurities of the wood.

A further object of the invention is the provision of a separator for storage batteries which shall have the characteristics named above.

Certain woods as for instance cypress, Douglas fir, white cedar, red wood and like woods contain in their natural state no substance in sufiicient quantities to injure the ositive plates of a battery when in use, and I have found that such woods require only to have their porosity increased to a suitable degree in order to form serviceable and substantial battery separators. In these woods there is a sort of incrusted matter on the true wood fibers which is composed principally of gums, resins, coloring matters and like substances. This matter occupies the spaces between the. fibers of the wood. If the separators are placed in the ibfliiglfilfy with the wood in its natural state, th incrusting matters during the opei'ationof the battery are oxidized forming carbon-dioxid and water as the main products. By removing the incrusting matters before using the separator in a battery, advantages are obtained, in addition to that of increasing the porosity as already referred to,,among which may be Specification of Letters Patent.

atented Sept. 13, 1921.

Application filed August 24, 1916. Serial No. 118,594.

mentioned the increased efiiciency of the batter especially during the first discharges I cause by the prevention of the loss of electrical energy which takes place when partof in oxidizing the inthe current is used u crusting matters. he increasing of the porosityincreases the ampere hour capacity I of the battery as the internal resistance of the battery is reduced and it also aids the difl'usion of the acid to make up for the weakening of the electrolyte in the pores of the plates. The treatment required for the separator is one which will remove the substance .named above and which clog the ores of the wood, but which will not attac the wood fiber proper to any appreciable extent, leaving the wood structurally strong and yet porous.

Boiling the wood in water or treating it with steam will dissolveout some of the insulating'compoundsbetween the fibers of the wood but does not remove the clogging material referred to so as to give that and other advantages re uired for t e most eflicient operationof the attery.

orosity v Treatment-of the wood with solutions of causticv soda also fail to give the desired character of -separator.- Such treatment mellows' and softens the fiber and causes the material to swell into a ally weak mass. y

I have found that-the substances named above as impurities may be effectively removed by treatment in a dilute solution of a sulfite which may be an acid sulfite. 'The bodies of wood shaped as'separators are immersed in such a solution and allowed to remain for a length. of time and at a temperature which dependsupon the kind of wood used and the degree'of porosity desired. An

example. of my invention and treatment is to soak the wood in a 5% solution of sodium' '85 soft and structun- 4 sulfite "at 180 Fahrenheit for {six hours,

allow the solution to cool and stand fora further period of about twelve hours after which the excess sulfite is removed with v ,I

water. During the 'secondperiod the products which are formed by the action of the sulfite diffuse out of the wood' The exact strength of the-solution used and the duration and temparature of the treatment are factors which depend on the kind and condition of the wood,'the porosity desired and i the timeavailable. In order to shorten the time of treatment the wood may be treated with a stronger solution than 5% ,under pressure in a digester. Other sulfites or acid sulfites may be substituted for the sodium" sulfite as for example potassium sulfite and calcium acid sulfite. The strength of the solution used is such that the various clogging matters are removed without the wood.

fiber itself being appreciablyattacked, this leaving the wood fiber of the separator structurally strong. The wood fibers are more wiry and stronger than by the other methods of treatment referred to. For instance the caustic soda method softens and Inellows the fiber while fibers ot' the separator pro duced by the present invention are harsh and strong, the difference between the fibers in the two cases corresponding roughly to the difference between linen and cotton fibers.

While the invention has been illustrated of gums, resins and other substances, not an integral part of the true wood fiber, by immersing in a solution of a sulfite and heating the solution to such temperature and for such time as produces the porosity desired, the wood of the finished separator containing a small quantity of gum. resin and other 7 August, 1916.

substances, not an integral part of the true wood fiber, relative to those naturally existing in the wood.

2. The process of preparing battery separators which consists in shaping wood contaming no substance in sufiicient uantity to 1n ure the positlve battery plate, increasing the size of the fluid passages through the wood by the removal of gunis, resins and other substances, not an integral part of thetrue Wood fiber, by soaking the wood in a five (5%) per cent. solution of sodium sulfite at a temperature of 180 Fahrenheit for six (6) hours, allowing the solution tostand and cool for twelve (12) hours and IGII10V' ing the excess sulfite with water,the Wood of the finished separator. containing a small quantity of gums, resinsand other substances, not an integral part of the true wood fiber, relativeto those naturally existing in the wood 3. A battery separator which consists of awood naturally containing no substances in sufficient quantity to injure the positive battery plates, the fluid passages through the wood being relatively increased'in size by the removal of gums, resins and other substances, not an integral part of the true wood fiber, by immersing in a solution ofa sulfite and heating the solution to such -temperature and for such time as produces the porosity desired, the wood of the finished separator containing a small quantity of gum, resins and other substances not an integral part of the true wood fiber, relatively to those naturally existing in the Wood.

In testimony whereof, I have signed my name to this specification this 23rd day of DAVID FOSTER GOULD. 

